This gem, dug out deep from the bowels of Tokyo's Akihabara shopping district, is a smartphone cordless speakerphone dock with a difference. It picks up and transmits audio to and from your smartphone not by Wi-Fi, Bluetooth, or any other kind of radio communication; but simple mutual-induction.
Called "Thanko" locally, the speakerphone greatly amplifies whatever your smartphone squeaks out, without being in the "speakerphone" mode; while its mic captures your voice with high-gain, and relays it to your phone. A lot of things could go wrong (feedback), but given that it made it to the noisy Tokyo market, those issues may have been addressed. The dock can stay plugged in to a wall-socket, and can charge your smartphone over USB; or you can unplug it, and its 800 mAh battery can keep it going for a few hours.